1. Field of the Invention
The present invention relates to an analog to digital (A/D) converter. More particularly, the present invention relates to an A/D converter of a parallel type which converts analog signals to digital signals using Micro Electro-Mechanical System (MEMS) technology.
2. Description of the Related Art
Diverse signals in nature change to analog continuously over time. In order to understand such a phenomenon in nature, the size of the analog signals need to be measured over time. The values are processed and analyzed using a computer, but in order for the computer to process and analyze analog signals, a device for converting the analog signals into digital values which are able to be processed in the computer is required. Such a device is an analog to digital (A/D) converter.
An A/D converter may be fabricated using Micro Electro-Mechanical System (MEMS) technology. MEMS technology may also be referred to as micro systems, micromachines, or micro mechatronics, and means developing mechanical devices with microscopic precision machinery technology. The A/D converter can be miniaturized using MEMS technology.
A/D converters include parallel comparator, single-slope, dual-slope, and successive approximation type A/D converters, among which an A/D converter of parallel comparator type uses an operational (OP) amplifier as a comparator, and encodes an output signal of the comparator to output a digital value in binary code. The comparator outputs a voltage corresponding to logical value 1 if an input voltage is higher than a reference voltage.
Such an A/D converter of parallel comparator type consists of a plurality of resistors to set a reference voltage, a plurality of comparators to compare voltages to each reference voltage, and an encoder to output digital signals.
However, the plurality of resistors and comparators have high power consumption. In addition, more resistors and comparators are required in order to implement higher resolution and higher speed, resulting in higher power consumption. In particular, an n-bit A/D converter requires a 2n number of resistors and a 2n-1 number of comparators, so power consumption of an A/D converter of a larger number of bits increases exponentially.
Therefore, there is a need for an A/D converter having high resolution and high speed, but low power consumption.